Some tests in aiosmtpd/tests/test_server.py hang with python 3.12

[kapouer]

This is on debian/trixie, using aiosmtpd 1.4.4.post2-1 or 1.4.3.
It hangs even when there is an actual online network (it also hangs in a restricted container).

This one for example:

python3.12 -m pytest -v -k test_unknown_args_direct 
/usr/lib/python3/dist-packages/nose/config.py:142: SyntaxWarning: invalid escape sequence '\.'
  """nose configuration.
Test session starts (platform: linux, Python 3.12.1, pytest 7.4.4, pytest-sugar 0.9.7)
cachedir: .pytest_cache
rootdir: /home/dev/Software/debian/python-aiosmtpd/salsa
configfile: pyproject.toml
plugins: click-1.1.0, sugar-0.9.7, env-0.8.2, pyfakefs-5.3.2, asyncio-0.20.3, order-1.0.1, subtests-0.11.0, xdist-3.4.0, timeout-2.2.0, mock-3.12.0, flaky-3.7.0, case-1.5.3, django-4.5.2
asyncio: mode=Mode.STRICT
collected 565 items / 564 deselected / 1 selected

Works with python3.11
Maybe it's because some plugin is not up-to-date ?

I played with it a little and any clue might unblock the situation.